/*      $OpenBSD: accept.c,v 1.6 2021/12/13 16:56:49 deraadt Exp $      */
/*
 *      Written by Artur Grabowski <art@openbsd.org>, 2002 Public Domain.
 */
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/un.h>

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>
#include <signal.h>
#include <string.h>

#define SOCK_NAME       "test-sock"

int     child(void);

int
main(int argc, char *argv[])
{
        int listensock, sock;
        struct sockaddr_un sun, csun;
        int csunlen;
        int fd, lastfd;
        int status;
        int ischild = 0;

        /*
         * Create the listen socket.
         */
        if ((listensock = socket(PF_LOCAL, SOCK_STREAM, 0)) == -1)
                err(1, "socket");

        unlink(SOCK_NAME);
        memset(&sun, 0, sizeof(sun));
        sun.sun_family = AF_LOCAL;
        strlcpy(sun.sun_path, SOCK_NAME, sizeof sun.sun_path);


        if (bind(listensock, (struct sockaddr *)&sun, sizeof(sun)) == -1)
                err(1, "bind");

        if (listen(listensock, 1) == -1)
                err(1, "listen");

        switch (fork()) {
        case -1:
                err(1, "fork");
        case 0:
                return child();
        }

        while ((fd = open("/dev/null", O_RDONLY)) >= 0)
                lastfd = fd;

        switch (fork()) {
        case -1:
                err(1, "fork");
        case 0:
                ischild = 1;
                close(lastfd);  /* Close one fd so that accept can succeed */
                sleep(2); /* sleep a bit so that we're the second to accept */
        }
        
        sock = accept(listensock, (struct sockaddr *)&csun, &csunlen);

        if (!ischild && sock >= 0)
                errx(1, "accept succeeded in parent");
        if (ischild && sock < 0)
                err(1, "accept failed in child");

        while (!ischild && wait4(-1, &status, 0, NULL) > 0)
                ;

        return (0);
}

int
child()
{
        int i, fd, sock;
        struct sockaddr_un sun;

        /*
         * Create socket and connect to the receiver.
         */
        if ((sock = socket(PF_LOCAL, SOCK_STREAM, 0)) == -1)
                errx(1, "child socket");

        (void) memset(&sun, 0, sizeof(sun));
        sun.sun_family = AF_LOCAL;
        (void) strlcpy(sun.sun_path, SOCK_NAME, sizeof sun.sun_path);

        if (connect(sock, (struct sockaddr *)&sun, sizeof(sun)) == -1)
                err(1, "child connect");

        return (0);
}